1. Field of the Invention
The present invention relates to a nebulizer for dispensing medicament with associated means for counting doses administered by the nebulizer.
The present invention preferably relates to nebulisers in the form of inhalers. In particular, the invention relates to so-called Metered Dose Inhalers (MDIs), i.e. inhalers in which a liquid medicament formulation is dispensed as an aerosol, or nebulised, from a pressurised container (aerosol container) by means of a metering valve, in particular. However, the present invention can also be used for other inhalers or nebulisers in which it is important to count the number of doses dispensed.
2. Description of Related Art
WO 00/09187 A1, which constitutes the starting point, discloses an MDI with a counting device for counting actuations and/or aerosol doses dispensed. On actuation, a container that holds the medicament formulation to be dispensed is pressed into a housing of the MDI. This stroke movement is detected by the counting device and drives a counting ring. For this purpose, the counting device has an elastically deformable drive element resembling a bell-crank lever. When the MDI is actuated, the drive element is moved both axially and in the direction of rotation (circumferential direction) of the counting ring at the same time, so as to rotate the counting ring further.
The elastic deformation of the drive element in the known MDI may be problematic. In particular, satisfactory resetting of the drive element is absolutely necessary if problem-free operation of the counting device is to be guaranteed. This requires very narrow manufacturing tolerances.
A further problem or disadvantage of the known MDI is the fact that incomplete actuation—i.e. where the container is only partly moved—does not ensure that the counting device or counting ring is reliably moved on, even when a dose is dispensed in spite of only partial actuation.